1. Field of the Invention
The present invention relates to a word processor unit, more specifically, to a word processor unit with document display function which executes the document retrieval of a large number of created, edited, and stored documents and displays them as is necessary.
2. Description of the Related Art
Word processors use input devices, such as keyboards or mice, to input code information for text, tables and figures, and after editing, store the code information as it is. Here, code information, rather than being inputted as a unified data construction consisting of 2-dimensional graphic information (bit map image) using a scanner to read text and figures on a piece of paper, is inputted as character code data and attribute code data (such as character size, kind of character) for characters and tables, and as figure code data (figure type, end point position) and feature code data (line width, coloring-in) for figures, meaning a document consisting of a plurality of data constructions is inputted as code information.
The object of this kind of unit is usually to have the created document printed by a high resolution (for example 400 dots/inch (dpi)) printer on paper which can be of A4, or B4, or one of a variety of other sizes. Therefore, to create a high quality print output of the document, of which the appearance and quality are in line with the intentions of the operator, a large amount of attribute code data is inputted and stored at the same time as when the document is created. Moreover, the majority of documents created using word processors are inputted using character code as the base (character-based input being the mainstream, with graphics-based input being less common), so that the document is constructed of characters and character-based line figures (a figure constructed, not of bit map data, but of a sequence of line segments, each of which is defined as one single character). That is to say, a large amount of attribute code data for the various kinds of character decoration is added to the code data for each separate character, as well as the character code data array which shows the kind of line constructed for the character-based line figures described above. In this way, by taking a unified data construction for all different characters, then the data processing (such as deleting, inserting, copying, or moving) when creating and editing the document can be undertaken for the unified character information, facilitating high speed editing of the document. However, regardless of whether the stored information is in this form, otherwise known as code information, the amount of data for one document remains large.
On the other hand, the storage of a large amount of code is achieved by means of magnetic disks, such as flexible disks or optical magnetic disks which, while rather slow when compared to semiconductor memory, are inexpensive and can be removed, allowing easy management of data.
In order to view a desired document out of all of the documents stored in the converted form as code information, then it becomes desirable for the operator to make use of a word processor unit which uses a document retrieval unit whereby the operator can retrieve the document and visually examine it, with direct consecutive display using a display device such as a CRT or a liquid crystal display which, when compared to the printer output, has a small screen (for example, 640*400 pixels) with low resolution (for example, 100 dpi). To provide a document retrieval device which allows the operator to efficiently visually refer to the document, the following two conditions are necessary.
(1) Rather than providing an image of the same high quality as the final printed image which would take considerable time, the device should allow the operator to consecutively view the document, simplified or divided up to an extent which may be specified by the operator, at a given high speed.
(2) It should be possible for the operator to stop the consecutive display of the chosen document at a certain spot, and to have the preceding or the following document(s) generated one at a time at high speed.
Means for achieving the high-speed consecutive retrieval, which use scanners to input a 2-dimensional (bit map image) comprised of text, tables and images, and then display an expanded display of compressed image data have already been described at length (For example, U.S. Pat. No. 5,129,011 issued on Jul. 7, 1992). However, this has not been the case for a document retrieval unit where documents are input and stored as code information before being retrieved and consecutively displayed at high speed.
This has been mainly for the following two reasons:
(1) In reading the documents stored on magnetic disks in low-speed devices, in addition to the time taken to transmit the data, it is necessary to include the time taken for the reader head to find the correct location (seek time and rotation time), hence making the process time-consuming.
(2) Since the data is constructed so that attribute data is assigned to each separate character, in generating the display image it becomes necessary to read this attribute data for each character, and, having selected the font ROM etc. in accordance with this attribute data, to develop the bit map image, all-in-all a troublesome process which must be undergone for every character in the document, taking a considerable amount of time.